Applications of excimer lasers to laser-radar observations of the upper atmosphere

Development of efficient ultraviolet (UV) rare-gas halide excimer lasers has added new possibilities for laser radar (lidar) technique for monitoring atmospheric constituents. An experimental result of the observation of the stratospheric ozone layer by a XeCl laser (308 nm) based on the differential-absorption-lidar (DIAL) technique is described. The obtained ozone profile in an altitude range of 15- 25 km are in good agreement with those measured by radiosonde. The measurement error is analyzed for one-wavelength lidar. The accuracy is estimated to be 10-30 percent within an altitude range of 10-30 km and at a range resolution of 1 km or less. The accuracy and the resolution are higher than the Umkehr method. Recent progress of rare-gas halide lasers and their frequency conversion techniques as a transmitter for lidar are reviewed. Many powerful and reliable new sources are available in almost every wavelength over the near UV region. New applications of these UV sources to the lidar system are also briefly discussed, especially from the scientific field on the middle atmosphere.